1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 48:2010Rubber, vulcanized orthermoplastic Determinationof hardness (hardness between10 IRHD and 100 IRHD)BS ISO 48:2010 BRITISH STANDARDNational forewordThis British Stand
2、ard is the UK implementation of ISO 48:2010. Itsupersedes BS ISO 48:2007 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/22, Physical testing of rubber.A list of organizations represented on this committee can beobtained on request to its secretary.
3、This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 69658 9ICS 83.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under
4、the authority of theStandards Policy and Strategy Committee on 30 September 2010.Amendments issued since publicationDate Text affectedBS ISO 48:2010Reference numberISO 48:2010(E)ISO 2010INTERNATIONAL STANDARD ISO48Fifth edition2010-09-15Rubber, vulcanized or thermoplastic Determination of hardness (
5、hardness between 10 IRHD and 100 IRHD) Caoutchouc vulcanis ou thermoplastique Dtermination de la duret (duret comprise entre 10 DIDC et 100 DIDC) BS ISO 48:2010ISO 48:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be pri
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10、1 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reservedBS ISO 48:2010ISO 48:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references2 3 Terms and definitions .2 4 Principle3 5
11、Apparatus.3 5.1 General .3 5.2 Methods N, H, L and M 3 5.3 Methods CN, CH, CL and CM .5 6 Test pieces .5 6.1 General .5 6.2 Methods N, H, L and M 6 6.3 Methods CN, CH, CL and CM .7 7 Time interval between vulcanization and testing.7 8 Conditioning of test pieces 7 9 Temperature of test .7 10 Procedu
12、re.7 11 Number of readings.8 12 Expression of results8 13 Precision.8 14 Test report11 Annex A (informative) Empirical relationship between indentation and hardness12 Annex B (informative) Precision results from interlaboratory test programmes.14 Annex C (informative) Guidance for using precision re
13、sults .22 Bibliography23 BS ISO 48:2010ISO 48:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out thr
14、ough ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collabo
15、rates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Stand
16、ards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of
17、this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 48 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis. This fifth edition cancels and replaces the f
18、ourth edition (ISO 48:2007), of which it constitutes a minor revision intended to update the precision statements in Annex B. It also incorporates the Technical Corrigendum ISO 48:2007/Cor.1:2009. BS ISO 48:2010ISO 48:2010(E) ISO 2010 All rights reserved vIntroduction The hardness test specified in
19、this International Standard is intended to provide a rapid measurement of rubber stiffness, unlike hardness tests on other materials which measure resistance to permanent deformation. Hardness is measured from the depth of indentation of a spherical indentor, under a specified force, into a rubber t
20、est piece. An empirical relationship between depth of indentation and Youngs modulus for a perfectly elastic isotropic material has been used to derive a hardness scale which can conveniently be used for most rubbers. When it is required to determine the value of Youngs modulus itself, it is expecte
21、d that an appropriate test method be used, for example that described in ISO 7743. The guide to hardness testing, ISO 18517, can also be a useful reference. BS ISO 48:2010BS ISO 48:2010INTERNATIONAL STANDARD ISO 48:2010(E) ISO 2010 All rights reserved 1Rubber, vulcanized or thermoplastic Determinati
22、on of hardness (hardness between 10 IRHD and 100 IRHD) WARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to
23、establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. CAUTION Certain procedures specified in this International Standard may involve the use or generation of substances, or the generation of waste, that could constitute a local environme
24、ntal hazard. Reference should be made to appropriate documentation on safe handling and disposal after use. 1 Scope This International Standard specifies four methods for the determination of the hardness of vulcanized or thermoplastic rubbers on flat surfaces (standard-hardness methods) and four me
25、thods for the determination of the apparent hardness of curved surfaces (apparent-hardness methods). The hardness is expressed in international rubber hardness degrees (IRHD). The methods cover the hardness range from 10 IRHD to 100 IRHD. These methods differ primarily in the diameter of the indenti
26、ng ball and the magnitude of the indenting force, these being chosen to suit the particular application. The range of applicability of each method is indicated in Figure 1. This International Standard does not specify a method for the determination of hardness by a pocket hardness meter, which is de
27、scribed in ISO 7619-2. This International Standard specifies the following four methods for the determination of standard hardness. Method N (normal test) is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD, but can also be used for hardnesses in the range 30 IRHD to 95 IRHD.
28、Method H (high-hardness test) is appropriate for rubbers with a hardness in the range 85 IRHD to 100 IRHD. Method L (low-hardness test) is appropriate for rubbers with a hardness in the range 10 IRHD to 35 IRHD. Method M (microtest) is essentially a scaled-down version of the normal test method N, p
29、ermitting the testing of thinner and smaller test pieces. It is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD, but can also be used for hardnesses in the range 30 IRHD to 95 IRHD. NOTE 1 The value of the hardness obtained by method N within the ranges 85 IRHD to 95 IRHD and
30、 30 IRHD to 35 IRHD might not agree precisely with that obtained using method H or method L, respectively. The difference is not normally significant for technical purposes. NOTE 2 Because of various surface effects in the rubber and the possibility of slight surface roughness (produced, for example
31、, by buffing), the microtest might not always give results agreeing with those obtained by the normal test. BS ISO 48:2010ISO 48:2010(E) 2 ISO 2010 All rights reservedThis International Standard also specifies four methods, CN, CH, CL and CM, for the determination of the apparent hardness of curved
32、surfaces. These methods are modifications of methods N, H, L and M, respectively, and are used when the rubber surface tested is curved, in which case there are two possibilities: a) the test piece or product tested is large enough for the hardness instrument to rest upon it; or b) the test piece or
33、 product tested is small enough for both the test piece and the instrument to rest upon a common support. A variant of b) would be where the test piece rests upon the specimen table of the instrument. Apparent hardness can also be measured on non-standard flat test pieces using methods N, H, L and M
34、. The procedures described cannot provide for all possible shapes and dimensions of test piece, but cover some of the commonest types, such as O-rings. This International Standard does not specify the determination of the apparent hardness of rubber-covered rollers, which is specified in ISO 7267 (a
35、ll parts). Key X hardness (IRHD) aMethod L and method CL. bMethods N and M and methods CN and CM. cMethod H and method CH. Figure 1 Range of applicability 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the
36、edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 18898, Rubber Calibration and verification of hardness testers ISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test method
37、s 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. BS ISO 48:2010ISO 48:2010(E) ISO 2010 All rights reserved 33.1 international rubber hardness degree scale IRHD scale hardness scale chosen so that 0 represents the hardness of material having a Yo
38、ungs modulus of zero and 100 represents the hardness of a material of infinite Youngs modulus NOTE The following characteristics applying over most of the normal range of hardnesses: a) one international rubber hardness degree always represents approximately the same proportional difference in Young
39、s modulus; b) for highly elastic rubbers, the IRHD and Shore A scales are comparable. 3.2 standard hardness hardness obtained using the procedures described in methods N, H, L and M on test pieces of the standard thickness and not less than the minimum lateral dimensions specified NOTE Standard hard
40、ness is reported to the nearest whole number in IRHD. 3.3 apparent hardness hardness obtained using the procedures described in methods N, H, L and M on test pieces of non-standard dimensions, as well as hardness values obtained using methods CN, CH, CL and CM NOTE 1 Apparent hardness is reported to
41、 the nearest whole number in IRHD. NOTE 2 Values obtained by methods CN, CH, CL and CM are always given as apparent hardnesses since tests are commonly made on the complete article where the thickness of the rubber can vary and, in many cases, the lateral dimensions might not provide the minimum dis
42、tance between the indentor and the edge necessary to eliminate edge effects. Thus the readings obtained do not in general coincide with readings obtained on standard test pieces as defined in methods N, H, L and M or on a flat parallel-faced slab of the same thickness as the article. Moreover, the r
43、eadings might depend appreciably on the method of support of the article and whether or not a presser foot is used. Therefore, results obtained on curved surfaces are arbitrary values applicable only to test pieces or articles of one particular shape and of particular dimensions, and supported in on
44、e particular way, and in extreme cases such values can differ from the standard hardness by as much as 10 IRHD. Furthermore, surfaces that have been buffed or otherwise prepared to remove cloth markings, etc., can give slightly different hardness values from those with a smooth, moulded finish. 4 Pr
45、inciple The hardness test consists in measuring the difference between the depths of indentation of a ball into the rubber under a small contact force and a large (indenting) force. From this difference, multiplied when using the microtest by the scale factor 6, the hardness in IRHD is obtained from
46、 Tables 3 to 5 or from graphs based on these tables or from a scale, reading directly in IRHD, calculated from the tables and fitted to the indentation-measuring instrument. These tables and curves are derived from the empirical relationship between indentation depth and hardness given in Annex A. 5
47、 Apparatus 5.1 General Calibration and verification of the apparatus shall be performed in accordance with ISO 18898. 5.2 Methods N, H, L and M The essential parts of the apparatus are as specified in 5.2.1 to 5.2.6, the appropriate dimensions and forces being shown in Table 1. BS ISO 48:2010ISO 48:
48、2010(E) 4 ISO 2010 All rights reserved5.2.1 Vertical plunger, having a rigid ball or spherical surface on the lower end, and means for supporting the plunger so that the spherical tip is kept slightly above the surface of the annular foot prior to applying the contact force. 5.2.2 Means for applying
49、 a contact force and an additional indenting force to the plunger, making allowance for the mass of the plunger, including any fittings attached to it, and for the force of any spring acting on it, so that the forces actually transmitted through the spherical end of the plunger are as specified. 5.2.3 Means for measuring the increase in depth of indentation of the plunger caused by the indenting force, either in metric units or reading directly in IRHD. The gauge employed may be mechanical, optical or electrical. 5.2
